Hydrocarbon reforming



United States Patent Office 3,506,417 Patented Apr. 14, 1970 3,506,417HYDROCARBON REFORMING Harold J. Hepp and E. 0. Box, Jr., Bartlesville,kla., as-

signors to Phillips Petroleum Company, a corporation of Delaware N0Drawing. Filed May 13, 1966, Ser. No. 549,799 Int. Cl. Cg 11/02, 11/04US. Cl. 48197 4 Claims ABSTRACT OF THE DISCLOSURE This invention relatesto the production of methanecontaining gases fungible with natural gasfrom nonmethane containing feedstocks. In accordance with one aspect,this invention relates to the conversion of hydrocarbons containing from2 to 15 carbon atoms per molecule to a gaseous product rich in methaneby contacting in the presence of steam with a nickel or rutheniumcatalyst. In accordance with another aspect, this invention relates tothe conversion of light hydrocarbons such as propane to a gaseousproduct rich in methane, fungible with natural gas, with an alkalizednickel or platinium group metal catalyst in the presence of steam.

Utility companies which distribute gas for household or other use havean increasingly acute need for an economical means of supplying gasduring peak-load periods, During cold weather, for example, demand maybe double or triple the volume used on a mild day. In many instances,this peak-load demand is met by adding propane-air mixtures to the gas.Because the quantity of propane-air that can be blended is limited,there is a need for an economic process that can be used to supplypeakload demand.

Accordingly, the present invention relates to an improved process forthe production of methane-containing gases fungible with natural gasfrom hydrocarbon feedstocks.

An object of this invention is to provide a new and improved catalystfor the conversion of a hydrocarbon to methane-rich gas.

Another object of this invention is to provide a new and improvedcatalyst having increased catalyst life, useful for the steam reformingof hydrocarbons to produce methane-rich gaseous product.

Other aspects, objects, as well as the several advantages of theinvention will be apparent to one skilled in the art from a study ofthis disclosure and the appended claims.

According to the invention, a process is provided for the production ofmethane-containing gases fungible with natural gas from non-methanefeedstocks which comprises contacting said feedstock and steam at atemperature below about 1000 F. with an alkali metal or alkaline earthmetal promoted catalyst selected from (a) nickel and silica-containingsupports, and (b) supported platinum group metals.

The non-methane feedstocks processable to methanerich product accordingto the invention comprises hydrocarbons having from 2 to about 15 carbonatoms per molecule. Such feedstocks preferably contain predominantlyparaffinic hydrocarbon such as propane, butane, hexane, octane, decane,dodecane, pentadecane and the like. The hydrocarbon feedstock cancontain minor amounts of unsaturated materials when desired. The highermolecular weight hydrocarbons in the feedstock will ordinarily have amaximum boiling point of about 500 F.

The reforming temperature employed does not exceed 1000 F., andpreferably will be in the range 650 1000 F. The reaction pressure willordinarily be suflicient to maintain liquid phase conditions, such as100-500 p.s.i.g, The steam to hydrocarbon mol ratio is ordinarily atleast 2.5 to 1, generally in the range 2.5-6 to 1. The total gaseoushourly space velocity (GHSV) ordinarily ranges from SOD-40,000 volumesof gas per volume of catalyst per hour, calculated at 32 F. and oneatmosphere.

The nickel catalyst used in the process of our invention is preferably anickel-kieselguhr catalyst containing from 5 to 90 weight percent nickelon a reduced basis and 0.5 to 10 weight percent alkali or alkaline earthmetal. In this application, the values for weight percent are based onthe total weight of the catalyst. Instead of kieselguhr, other naturalor synthetic silica-containing material, such as silica, silica-alumina,silica-zirconia, the natural or synthetic crystalline aluminosilicates,and the like, can be used. The alkali metal or alkaline earth metal canbe applied to the catalyst as the hydroxide, carbonate, or other solublesalt. Potassium carbonate is a presently preferred alkaline material.

The nickel catalyst of the invention exhibits a considerably longercatalyst life than is obtained with known nickel-alumina catalyst. Thelonger life is a result of the fact that silica-containing supports areconsiderably more stable in the presence of steam thanalumina-containing supports. As a result of this higher steam stability,catalysts of the invention have a useful life 2 to 10 times longer thanthat of the alumina base catalyst.

The platinum group metals for use in this invention can be ruthenium,rhodium, osmium, iridium, platinum, palladium, or mixtures of suchmetals and/or their compounds can be used. Ruthenium is a presentlypreferred platinum group metal.

The platinum groupmetals can be incorporated into any of the knownnatural or synthetic refractory inorganic oxide materials known assupports such as alumina, silica, magnesia, zirconia, silica-alumina,the natural or crystalline aluminosilicates, and the like. The amount ofplatinum group metal present in the catalyst composition can vary from0.01 to 20 weight percent, preferably in amounts less than about 10percent by weight. The amount of alkali metal or alkaline earth metalpresent in the catalyst can range from 0.5 to 10 weight percent. Thealkali metal or alkaline earth metal can be applied as hydroxide,carbonate, or other soluble salt. The term soluble is intended toinclude either aqueous or nonaqueous solvents, although water ispresently preferred. Potassium carbonate is the presently preferredalkali or alkaline earth compound.

As is demonstrated by the specific working examples hereinbelow, steamreforming of hydrocarbons according to the invention results in agaseous product fungible with natural gas, which product contains asmuch as 92 mol percent methane.

In actual operation, according to the invention, the steam reformingzone is charged with the catalyst, which includes an alkali or alkalineearth metal compound such as potassium carbonate, sodium carbonate,lithium carbonate, potassium bicarbonate, sodium bicarbonate, lithiumbicarbonate, potassium acetate, barium acetate, magnesium nitrate,beryllium nitrate, strontium nitrate, strontium acetate, bariumhydroxide, cesium bicarbonate, cesium hydroxide, rubidium carbonate,rubidium nitrate, calcium nitrate, calcium chromate, potassiumdichromate, potassium hydroxide, sodium hydroxide, lithium hydroxide,and the like. Mixtures of the alkali metal and/or alkaline earth metalcompounds can also be employed. It is to be understood that the termcatalyst as employed herein is intended to include the contact mass asprepared and charged to the reaction zone, that is, for example, nickelor ruthenium, or the oxide or salt thereof, in combination with thealkali or alkaline earth metal compound and a support material, as wellas any modifled physical or chemical form to which the contact mass canbe converted prior to or during the course of the steam reformingprocess.

The catalyst can be prepared by any of the known procedures. Ordinarily,the support, in the form of discrete particles, is impregnated with asolution of the desired nickel or platinum group metal compound,followed by calcining, impregnation with a solution of an alkali oralkaline earth metal compound, followed by calcining. Reduction withhydrogen can be done at any time subsequent to addition of the metal,either prior to or during use.

EXAMPLE I A catalyst used to demonstrate the process of the inventionwas an alkali metal-promoted nickel kieselguhr in the form of /s-inchpellets. The nickel content was 72 weight percent (after reduction) andthe potassium carbonate content was 1.6 weight percent (equivalent to0.9 percent potassium). It was prepared by impregnating kieselguhr withan aqueous solution of a soluble nickel salt, calcining, impregnatingwith aqueous potassium carbonate, calcining, and reducing in hydrogenfor about 7 hours at 650 F. and 1 hour at 840 F. Results obtained inreforming propane with steam were:

Run Number 1 Temperature, F. 840 Pressure, p.s.i.g 325 GHSV, total h 818H O/C H ratio, mol 4.0 Efl'luent gas composition, mol percent (dry):

H 7.0 CH 77.1 C 03 CO 6 C3H3 I111 CO free basis, mol percent (dry):

H 8.3 CH 91.3 C0 0 4 Heating value, B.t.u. cu. ft.:

Dry, 60 F./30 Hg 952 Saturated, 60 F./30" Hg 935 Wobbe Number, W 1304Weaver Flame Speed Factor, S 16.4

EXAMPLE II A catalyst used to further demonstrate the process of ourinvention was an alkali-promoted ruthenium-alumina in the form ofAs-inch pellets. The ruthenium content was 0.5 weight percent and thepotassium carbonate content Was 1.6 Weight percent (equivalent to 0.9percent potassium). It Was prepared by impregnating alumina with anaqueous solution of a soluble ruthenium salt, calcining, impregnatingwith an aqueous solution of potassium carbonate, calcining, and reducingin hydrogen for 1 hour at 800 F. Results obtained in reforming propanewith steam are:

Run Number 2 3 4 Temperature, F 798 863 1, 020 Pressure, p.s.i.g 320 320320 Space velocity, total, GHSV 3, 780 3, 070 3, 710 HzQ/CsHa ratio, mol4. 0 2. 7 3. 7 Effluent gas composition, mol percent (dry):

H 8.6 6.4 23.3 74. 4 78. 3 58. 6 0. 6 0. 5 1. O 14. 7 14. 2 17. 1 1. 7Nil Nil 10. 3 7. 5 28. 1 89. 0 91. Q 70. 7 C0 0. 7 0. 6 1. 2 Heatingvalues, B.t.u./cu. It;

Dry, 60 F./30 Hg 940 959 813 Saturated, 60 F./30 Hg 923 942 792 Wobbenumber, W 1, 290 1, 320 1, 250 Weaver flame speed, S 17. 0 16. 2 23. 9

Interchangeability or fungibility of other gases with natural gas isrelated to a number of factors, the major ones of which are (1) thetendency of the flame to flash back, (2) the tendency of the flame tolift off the burner, and (3) the tendency of the gas to burnincompletely. As a result of studies made by a number of workers, thefollowing diagram has been developed by P. Delbourg (Compt. rend. congr.ind. gaz, 68th Congr., Paris, 1951, 744-96) for the limits ofinterchangeability of other gases with natural gas:

Weaver Flame Speed Factor S In this diagram the Wobbe Number is relatedto the calorific value of the gas (in B.t.u. per cubic foot) by thefollowing equation:

W=calorific value/ (specific gravity) Calculation of the Weaver FlameSpeed Factor S is described in J. Res. Natl. Bur. Stds., 46, 213-245(1951).

It is apparent that the product of the process of our invention fallswithin the area of fungi-bility, and is thus a highly desirable materialfor use in meeting peak-load demand.

It is further apparent that the product of a run made according to theprior art falls outside the area of fungibility.

Reasonable variation and modification are possible within the scope ofthe foregoing disclosure and the appended claims to the invention, theessence of which is that there is provided process for the production ofmethane-containing gases fungible with natural gas from nonmethanefeedstocks which comprises contacting such feedstocks at a temperaturebelow 1000" F. with steam and an alkalized nickel or platinum groupmetal catalyst.

We claim:

1. A process for the production of methane-containing gases fungiblewith natural gas from propane feedstocks which comprises contacting apropane feedstock and steam wherein the steam to hydrocarbon mol ratiois 2.5:1 to 6:1 with a catalyst selected from the group consisting of(a) silica supported nickel promoted with 05-10 weight percent, based onthe total catalyst, of a promoter selected from the group consisting ofalkali metals and alkaline earth metals, and

(b) a supported platinum group metal promoted with 05-10 weight percent,based on the total catalyst, of a promoter selected from the groupconsisting of alkali metals and alkaline earth metals at an elevatedtemperature of 650-1000 F. and a pressure of 100 500 p.s.i.g. and atotal GHSV of 50040000 to produce a reaction efiluent gas containing inexcess of 70 mol percent methane.

2. A process according to claim 1 wherein the amount of nickel in (a) isfrom 5-90 weight percent on a reduced basis and the amount of platinumgroup metal in (b) is from 0.01 to 20 weight percent.

3. A process according to claim 1 wherein the catalyst isnickel-kieselg-uhr promoted with potassium.

4. A process according to claim 1 wherein the catalyst isruthenium-alumina promoted with potassium.

References Cited UNITED STATES PATENTS Martin 252-472 X Michael et al252472 X Rottig 252472 Nonnenmacher 48-212 McMahon.

Anderson et al. 48-213 XR Dowden et al.

Taylor et al. 48-197 X Dowden 23-212 Taylor et a1. 48-214 X Feldkirchneret al 48-214 US. Cl. X.R.

